If you’re not already reading xkcd, then you should be. It’s full of gems like this one:

I sometimes wonder whether the first ten minutes of every school science class shouldn’t be just the chanting of “correlation does not imply causation” until everyone has it burned into their brains. So many misunderstandings of science would be cleared up.

Autism on the rise? Increased use of the MMR vaccine? Yes, there is correlation. Without an underlying mechanism however, there is no causation – and that’s where the science happens. We don’t really care that two things are happening at the same time unless there is something connecting the two. If there is, well designed experiments will help us figure it out.

Sometimes events are just correlated, nothing more. So, the next time someone tells you that Facebook gives you cancer or some other nonsense disguised as statistics, ask them to explain how exactly one causes another. Now, excuse me whilst I return to my morning chant…